I only have one 223, a 1:12" 24" Ultra Varmint, for carry I'd opt for a standard contour 22" or a Superlight, from colony shooting, the 24" bull barrel would be optimum, for a good combination the 22" bull barrel or standard contour would be my pick. Mine, like most 1:12" barrels, shoots the cheap Win White box Value pack 45gr JHP ammo that Walmart sells for $25 a box now, used to be $14 for 40 rounds, into well under 1" at 100yds.
Tim